Holding down is not breaking the rules. Refs blow penalties when they tell players to get off and the players take too long. Of course it is inconsistent because that's the nature of the rule - there is never going to be any 100% perfect black and white rule when the ref controls the speed of the ruck. There are way too many variables. We tried to clean it up a bit last year, penalising a lot more for holding down and punishing deliberate penalties, but what happened? Everyone whinged because let game flow
And that is also the reason why everyone bags out the ref, asks for more consistency when it actually is impossible to start with. The fact you get it is great, but tell those old commentators and journos as well.
But my point as well is that because the rule is written to be inconsistent, the penalties needs to better match the crime and advancing 20-40m for a kick down field might now be too great for the modern game.